Keepalived+Nginx+Tomcat 高可用负载均衡
一、4台机器角色
| 机器IP | 角色 | 服务 |
| 192.168.52.138 | Nginx1 + Keepalived Master | Nginx、Keepalived主 |
| 192.168.52.139 | Nginx2 + Keepalived Backup | Nginx、Keepalived备 |
| 192.168.52.135 | Tomcat1 | 后端应用 |
| 192.168.52.136 | Tomcat2 | 后端应用 |
VIP：192.168.52.100（对外入口）
二、所有机器通用初始化（4台都执行）
# 关闭防火墙、SELinuxsystemctl stop firewalldsystemctl disable firewalldsetenforce 0sed -i 's/^SELINUX=.*/SELINUX=disabled/'/etc/selinux/config# 安装基础依赖dnf install -y wget tar gcc make java-1.8.0-openjdk-devel三、Tomcat1（135）+ Tomcat2（136）配置（两台一样）
1. 安装 Tomcat 9
cd /usr/localwget https://archive.apache.org/dist/tomcat/tomcat-9/v9.0.85/bin/apache-tomcat-9.0.85.tar.gztar -zxvf apache-tomcat-9.0.85.tar.gzmv apache-tomcat-9.0.85 tomcat2. 写测试页面（区分两台）
# Tomcat1（135）执行echo "<h1>Tomcat-135</h1>">/usr/local/tomcat/webapps/ROOT/index.jsp# Tomcat2（136）执行echo "<h1>Tomcat-136</h1>">/usr/local/tomcat/webapps/ROOT/index.jsp3. 启动 Tomcat
/usr/local/tomcat/bin/startup.sh4. 验证（访问自己IP:8080）
curl localhost:8080四、Nginx1（138）+ Nginx2（139）安装（两台一样）
dnf install -y nginx配置 Nginx 反向代理 到 Tomcat
cat >/etc/nginx/nginx.conf <<EOFuser nginx;worker_processes auto;error_log /var/log/nginx/error.log;pid /run/nginx.pid;events { worker_connections 1024;}http { log_format main '\$remote_addr - \$remote_user [\$time_local] "\$request" ''\$status \$body_bytes_sent "\$http_referer" ''" \$http_user_agent" "\$http_x_forwarded_for"';access_log /var/log/nginx/access.log main; upstream tomcat_servers { server 192.168.52.135:8080; server 192.168.52.136:8080; } server { listen 80; server_name localhost;location/ { proxy_pass http://tomcat_servers; proxy_set_header Host \$host; proxy_set_header X-Real-IP \$remote_addr; } }}EOFAI写代码
启动 Nginx
systemctl enable --now nginx测试 Nginx 代理是否正常
curl localhost# 会交替出现 Tomcat-135/ Tomcat-136五、Keepalived 配置（核心：138主 + 139备）
1. 两台都安装 Keepalived
dnf install -y keepalived2. 配置 138（Master）
cat >/etc/keepalived/keepalived.conf <<EOFglobal_defs { router_id NGINX_MASTER}# 监控 Nginx 是否存活vrrp_script chk_nginx { script "killall -0 nginx" interval 2 weight -20}vrrp_instance VI_1 { state MASTERinterface ens160 # 改成你实际网卡名（ip addr 看） virtual_router_id 52 priority 150 advert_int 1 authentication { auth_type PASS auth_pass 123456 } virtual_ipaddress {192.168.52.100/24 } track_script { chk_nginx }}EOFAI写代码
3. 配置 139（Backup）
cat >/etc/keepalived/keepalived.conf <<EOFglobal_defs { router_id NGINX_BACKUP}vrrp_script chk_nginx { script "killall -0 nginx" interval 2 weight -20}vrrp_instance VI_1 { state BACKUPinterface ens160 # 改成你实际网卡名 virtual_router_id 52 priority 100 advert_int 1 authentication { auth_type PASS auth_pass 123456 } virtual_ipaddress {192.168.52.100/24 } track_script { chk_nginx }}EOFAI写代码
4. 两台都启动 Keepalived
systemctl enable --now keepalived六、最终测试（任意机器执行）
curl 192.168.52.100✅ 不断刷新会交替显示 Tomcat-135 / 136
✅ 停掉 138 的 Nginx 或 Keepalived，VIP 自动飘到 139
✅ 停掉任意一台 Tomcat，Nginx 自动跳过故障节点
七、你可能需要的排查命令
# 看VIP在哪ip addr# 看Keepalived日志tail -f /var/log/messages# 抓VRRP包tcpdump -i ens160 host 224.0.0.1